Galileo Galilei had discovered four moons orbiting Jupiter, includi

Question

Project SC Butler: Day 221: Sentence Correction (SC2) 
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Galileo Galilei  had discovered four moons orbiting Jupiter, including Ganymede, the largest moon in the solar system , by the time Christiaan Huygens discovered Titan, the largest moon of Saturn, in 1655.

A) had discovered four moons orbiting Jupiter, including Ganymede, the largest moon in the solar system

B) had discovered four moons orbiting Jupiter, which includes Ganymede, being the largest moon in the solar system

C) had discovered four moons, including Ganymede, orbiting Jupiter, which is the largest moon in the solar system

D) discovered four moons orbiting Jupiter, the largest moon in the solar system including Ganymede

E) discovered four moons orbiting Jupiter, including Ganymede, the largest moon in the solar system

generis · Accepted Answer

OFFICIAL EXPLANATION

Project SC Butler: Day 221: Sentence Correction (SC2)

• HIGHLIGHTS

Use past perfect!

→ BY THE TIME X, Y is a Big Signal: use past perfect.
This sentence uses that structure. The structure is reversed.

This sentence is a variation on "By the Time X, Y."
I will simply flip and rewrite the sentence:
  By the time  Christiaan Huygens discovered Titan, the largest moon of Saturn, in 1655, 
Galileo had discovered four moons orbiting Jupiter, including Ganymede, the largest moon in the solar system.

By the Time X, Y  is a signal to use past perfect.
Time X marks off a discrete point in the past.
Before that time, Y events happened.
To talk about the past of the past, we use past perfect, namely
HAD + PAST PARTICIPLE

• I see no errors. Keep. (See Notes, below.)

•  which  refers to an antecedent noun, and in this case, improperly refers to Jupiter
-- Jupiter does not include Ganymede. The four moons do.
-- but we know that  which  must refer   to Jupiter because the verb  includes  is  singular .
-- the verbal "being" is unnecessary 
Eliminate B 
 
• Um, Jupiter is definitely not the largest moon
(I hear the Indigo Girls' "Galileo" play in my head. (Linked below.) Levity is good.)
Eliminate C 
 
• we need past perfect  had discovered ] to talk about "the past of the past."
-- in order to emphasize that Galileo was far ahead of Huygens, we use  had discovered  (not just  discovered )
• The verb "discovered" is incorrect.
Eliminate D
 
• again, wrong verb. We need to use  had discovered,  not  discovered , as is used here. Same problem as that in D
Eliminate E

The best answer is A

NOTES

--   Some words and phrases indicate a time shift.   
One such phrase is
 By the time X, Y.  
Verbs must shift to reflect that time shift.

The Y events happen  before  the X event. 
Write X in simple past tense.
Write Y in past perfect (had verbED).

-- By the time X, Y  is fairly common on the GMAT. 
 
When we see the phrase in a question involving the past, almost without exception, 
(1) the Y events come before the X event, 
(2) Y events take past perfect, and 
(3) the X event takes simple past.

This sentence is a good example of contexts in which we should use past perfect (had verbED) for the earlier (Y) events rather than simple past.

By the time  means "when" or "at that time." 
Huygens made his discoveries at a discrete, defined time.
Huygens' discovery is the X event.

The X event rendered in  simple past  tense (discovered) creates a "stop right here" marker of something that happened before now. 
Then we use past perfect to describe the Y events before that marker.

By the time X, Y.  
By the time THIS thing happened (simple past), THIS other thing  had  happened (past perfect).

By the time  means   when  or  at THIS particular point in time.

We have  one  moment at which THIS thing happened in simple past tense. (Huygens discovered a moon of Saturn.)
-- Before that discrete moment in time there were other events, namely: Galileo had  already  discovered four moons of Jupiter.
-- Simply because of the way that English works, the specific language used in past perfect "announces" that we are speaking about things that happened BEFORE the event later or latest in time.

• Past perfect construction

If two or more events happen in the past and at least one of them is later in time than the other(s), we use  simple past tense  to describe the   later-in-time  event, and  past perfect  to describe the  events  that happened  before  that final event.

Past perfect is often described as  the past of the past .

Past perfect, active: HAD/HAVE + past participle (verbED)

Past perfect, passive: HAD/HAVE + been + past participle

Requirements? To use past perfect
(1) at least one event  must  be rendered in simple past tense (or we must know sequence from a time marker or stamp such as  by last Friday night , and
(2) often NO time sequence words such as  after, before,  or  subsequently  are present.

COMMENTS

ravigupta2912  , welcome to SC Butler.

As always  eakabuah  and  itoyj  , I am glad to have your contributions.

I wish I could have met Galileo. 
I make whimsical lists . . . such as "The 10 People I Wish I Could Have Met."

Then my lists grow. I think I am near 100 persons. 
But Galileo is Top Ten.

Well done, everyone. Kudos to all.

Not-so-random sidebar . . . any North Americans or music buffs recognize the words below  ? They're iconic.  
 I call on the resting soul of Galileo 
King of night vision, king of insight. 
That link is to the ORIGINAL VIDEO (the words in the video are not the lyrics).
The words on the original might confuse, though they're a great story.

This is a video with lyrics  -- a little hard to read, but good enough.
 Full lyrics are  here

itoyj · Answer

The largest moon in solar system must follow Ganymede as it is describing the moon

So we are left with A and E

E is eliminated as we require had in this

Answer A

Posted from my mobile device

eakabuah · Answer

I settled on A as well.

Meaning: Galileo had discovered four moons orbiting Jupiter. The discovered moons include Ganymede. Ganymede is the largest moon in the solar system. The discovery of four moons by Galileo took place by the time Huygens discovered Titan in 1655. The use of  had discovered  implies that Galileo's discovery took place before Huygens' discovery. The meaning is clear. Two events took place in the past at different points in time. One is clearly time-stamped, i.e. the discovery of Titan by Huygens. How do we know that Galileo's discovery precedes Huygens' discovery? The use of the past perfect  had discovered  removes this ambiguity. A is, therefore, the right answer.

There are no issues with this option. The use of the past perfect tense  had discovered  clearly clarifies the sequence of two events in A.  The largest moon in the solar system  rightly modifies  Ganymede  as the modifier in question touches the noun it modifies. Keep A.

The verb tense had discovered is correct. However, the relative clause which includes Ganymede modifies Jupiter instead of the discovery of four moons by Galileo. We can be considerate and say that which includes Ganymede modifies four moons. Then and again, we have a contest between a participial phrase and a relative clause. A phrase is more concise. Therefore, irrespective of how you look at it B is no contest for A. We also have  Ganymede ,  the largest moon in the solar system  vs  Ganymede ,  being  the largest moon in the solar system. Being is used incorrectly as a modifier in B. Eliminate B.

A moon orbiting another moon? No. That is illogical. The modifier  which is the largest moon in the solar system  is dangling. It is supposed to modify Ganymede. Eliminate C.

The verb tense discovered in D is incorrect. The use of the past tense in D makes it impossible for one to know which of the two events occurred before the other? Clearly, we know that Galileo's discovery occurred first, hence it has to be expressed in the past perfect tense. Eliminate D.

The same verb tense error in D is repeated in E.

A is left as the best answer.

ravigupta2912 · Answer

Galileo Galilei had discovered four moons orbiting Jupiter, including Ganymede, the largest moon in the solar system, by the time Christiaan Huygens discovered Titan, the largest moon of Saturn, in 1655.

A) had discovered four moons orbiting Jupiter, including Ganymede, the largest moon in the solar system

B) had discovered four moons orbiting Jupiter, which includes Ganymede, being the largest moon in the solar system

C) had discovered four moons, including Ganymede, orbiting Jupiter, which is the largest moon in the solar system

D) discovered four moons orbiting Jupiter, the largest moon in the solar system including Ganymede

E) discovered four moons orbiting Jupiter, including Ganymede, the largest moon in the solar system

Split - Past perfect needed to convey that GG had discovered X before CH did. D & E out.
B - incorrect usage of "which" - seems to modify Jupiter. Jupiter includes Ganymede? Illogical. Eliminated 
C - "which" incorrectly modifies Jupiter leading to meaning error. 
A - Correct answer.

ExpertsGlobal5 · Answer

Dear Friends,

Here is a detailed explanation to this question-

A:  This answer choice maintains proper modifier use and tense use, conveys the intended meaning of the sentence, and is concise. Thus, this answer choice is correct.

B:  This answer choice suffers from a modifier error; the phrase "which includes Ganymede" incorrectly refers to the noun "Jupiter", rather than the noun phrase "four moons". This modifier error is further compounded by the use of the verb "includes", which must refer to "Jupiter" as it is singular. B is also needlessly wordy, due to its use of the redundant verb "being". Thus, this answer choice is incorrect.

C:  This answer choice suffers from a modifier error; the phrase "which is the largest moon in the solar system" incorrectly refers to the noun "Jupiter", rather than the noun "Ganymede". Thus, this answer choice is incorrect.

D:  This answer choice suffers from a meaning error; the phrase "the largest moon in the solar system including Gayammede" modifies the noun "Jupiter", implying that Jupiter is the largest of all moons in the solar system, of which Gayanmede is one. D also suffers from a tense error, as it uses the simple past tense to refer to the earlier of two actions; the phrase "by the time Christiaan Huygens discovered..." refers to a discreet point in time and informs us that Gallileo's discovery took place before that time, meaning the past perfect tense must be used to refer to the act of making that discovery. Thus, this answer choice is incorrect.

E:  This answer choice repeats the tense error seen in Option D. Thus, this answer choice is incorrect.

Hence, A is the best answer choice.

To understand the concept of "Use of Which, Who, Whose, and Where on GMAT", you may want to watch the following video (~1 minute):

https://www.youtube.com/watch?v=e0M_MYzDfMk

To understand the concept of "Use of Being", you may want to watch the following video (~2 minutes):

https://www.youtube.com/watch?v=b2w9FNmjwtw

To understand the concept of "Past Perfect Tense - Use of Had on GMAT", you may want to watch the following video (~2 minutes):

https://www.youtube.com/watch?v=eFGxC37OOGU

All the best!
Experts' Global Team

iamdivs · Answer

four moons orbiting Jupiter, including Ganymede,

I think only option A made sense but what I am confused at is how including Ganymede modifies four moons,

I think it is modifying Jupiter no?

Thanks!

Posted from my mobile device

headofthetable · Answer

Galileo Galilei  had discovered four moons orbiting Jupiter, including Ganymede, the largest moon in the solar system , by the time Christiaan Huygens discovered Titan, the largest moon of Saturn, in 1655.

A) had discovered four moons orbiting Jupiter, including Ganymede, the largest moon in the solar system -  CORRECT .

B) had discovered four moons orbiting Jupiter, which includes Ganymede, being the largest moon in the solar system -   'Which' modifies Jupiter instead of moons as intended

C) had discovered four moons, including Ganymede, orbiting Jupiter, which is the largest moon in the solar system -  Stated this way, the sentence implies that Jupiter is the largest moon in the solar system.

D) discovered four moons orbiting Jupiter, the largest moon in the solar system including Ganymede -  Past perfect essential if 'By the Time' is used.

E) discovered four moons orbiting Jupiter, including Ganymede, the largest moon in the solar system -  same as D

VerbalBot · Answer

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Galileo Galilei had discovered four moons orbiting Jupiter, includi

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GMAT Sentence Correction (SC - EA only) Questions

Galileo Galilei had discovered four moons orbiting Jupiter, includi

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